California Code, Business and Professions Code - BPC § 18897.9

(a) Any agent contract that is negotiated by an athlete agent who fails to comply with this chapter, or has failed to comply with Chapter 1 (commencing with Section 1500) of Part 6 of Division 2 of the Labor Code, as repealed by Assembly Bill 1987 of the 1995-96 Regular Session, is void and unenforceable.

(b) No person shall owe an athlete agent any money or other consideration pursuant to an endorsement contract, financial services contract, or professional sports services contract negotiated by the athlete agent if the athlete agent fails to comply with this chapter, or has failed to comply with Chapter 1 (commencing with Section 1500) of Part 6 of Division 2 of the Labor Code, as repealed by Assembly Bill 1987 of the 1995-96 Regular Session.  The athlete agent shall refund any money or other consideration paid pursuant to that contract.